They are not sandbagging they just have stricter activity rules, I have been in both and prefer the guilds which expect participation if you sign up rather than wanting full sign up. They do not control MM.
380M is max reward tier for TW, in a large GP guild you do not need everyone to sign up to achieve that tier. So they shift towards strict participation rules and allow busy players to not signing up. Where as other guilds have not shifted from chasing EVERYONE to sign up, even when they don’t need it. Including the players who routinely get 0 or just 50 banners. These players are why you lose to more active guilds. Their GP placed you against your opponents then they do not use it, and you pay for it.
At 300M+ everyone should have 200 banners (full offense), more if partial defence which gives more.